Application of Ditch Magnet System to Extend Downhole Tool Life and Accuracy – Revealing the Quantity of Metal Contamination in Drilling Fluid

Magnetic contamination of drilling fluids is assessed. It is shown from experience how much material is typically removed from current drilling operations. Known sources for these materials are outlined, as well as the effect these materials have on down hole tools and measurements. To remove the materials a selection of strong rod magnets is positioned in a selected geometrical pattern either upstream or downstream the primary solids control equipment. Typical maximum field strength of the surface of Neodymium magnet rods is around 1.2 Tesla. Field experience from offshore operations in the North Sea and land-based drilling operations in the Permian basin have shown how such magnets can be efficient in removal of significant amounts of sub 50 micron magnetic materials that are contaminating drilling fluids. The quantity of the removed magnetic material and the consequent effect of removal of these materials are assessed for impact on cost reductions for downhole equipment wear and improved directional drilling operations. Furthermore, to add to the technology, data from more complicated ditch magnet systems used on offshore rigs are used to help quantify the amounts of detrimental material present in the drilling fluids. In the article, it is presented how modern ditch magnet systems work.